Structural member

ABSTRACT

The present invention relates to a structural member ( 10 ) for the use as a chord ( 41, 42 ) for forming a roof truss ( 40 ) for a building. The invention in one aspect broadly resides in an elongated open structural ( 10 ) member having a cross section including a minor flange ( 12 ), a major flange ( 13 ), and a web ( 14 ) interconnecting said flanges and having a section axis ( 11   a ) at right angles to the longitudinal axis ( 11   b ) of the structural member ( 10 ) and passing through the flanges ( 12, 13 ) and wherein said web ( 14 ) includes a linear portion ( 17 ) substantially coincident with the section axis ( 11   a ) and a divergent portion ( 18 ) which extends to one side of said section axis ( 11   a ); said minor flange ( 12 ) extends to said one side of said section axis ( 11   a ); said major flange ( 13 ) extends from said portion ( 18 ) to the opposite side of said section axis ( 11   a ), and the section configuration being such that an inverted and reversed corresponding open member is nestable within open structural member ( 10 ) with their respective linear section portions ( 17 ) alongside one another and with each minor flange ( 12 ) located in an abutting relationship against the underside of the adjacent major flange ( 13 ).

FIELD OF THE INVENTION

This application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/AU98/00316 which has an Internationalfiling date of Apr. 30, 1998 which designated the United States ofAmerica.

The invention relates to a structural member for construction ofbuildings such as houses. The invention has particular but not exclusiveapplication in use as a chord for forming a roof truss for a building.

PRIOR ART

A metal roof truss is commonly constructed with box-section chords andC-section web members. The box-section chords are formed by twoC-sections individually roll formed and then further fabricated bydimple formation for locating and/or fastening by welding, riveting,hole punched and bolted or screwed to close the two C-sections. Thefabrication of the section is a specialised operation and addsadditional cost and time to the manufacture of a chord.

Open sections are generally quicker and cheaper to manufacture thanbox-sections comprising two C-sections, but they lack the strength andstiffness required for chords. Thus, whenever open sections, such aschannel and Z-sections are used in the fabrication of building framesand roof trusses, additional precautions such as providing oversizedsections or additional structural support must be taken to compensatefor their inherent strength deficiencies. This of course increases thecost of many structures formed therefrom.

In addition, effecting the joints between top and bottom chords andbetween web members and chords mostly requires specialised joiningmembers or shaping for welding which adds to the cost and complexity ofsuch structures.

SUMMARY OF THE INVENTION

It is an object of this invention to provide an alternative structuralmember suitable for forming the chord of a truss or other structuralmember.

In one aspect the invention broadly resides in an elongated openstructural member having a cross-section including a minor flange, amajor flange and a web interconnecting said flanges and having a sectionaxis at right angles to the longitudinal axis of the structural memberand passing through the flanges and wherein:

said web includes a linear portion which extends substantiallycoincident with the section axis but substantially less than the lengthof the section axis between the flanges, and a divergent portion whichextends to one side of said section axis;

said minor flange extends to said one side of said section axis;

said major flange extends from said divergent portion to the oppositeside of said section axis, and

the section configuration being such that an inverted and reversedcorresponding open structural member is nestable within said openstructural member with their respective linear portions overlapping eachother and with each minor flange located in an abutting relationshipagainst the underside of the adjacent major flange.

In another aspect the invention broadly resides in an elongated openstructural member having a cross-section including a minor flange, amajor flange, and a web interconnecting said flanges and having asection axis at right angles to the longitudinal axis of the structuralmember and passing through the flanges and wherein:

said web includes a linear portion which extends substantiallycoincident with the section axis but substantially less than the lengthof the section axis between the flanges, and a divergent portion whichextends to one side of said section axis;

said minor flange laterally extends from said section axis to said oneside;

said major flange extends from said divergent portion to the oppositeside of said section axis, and

the section configuration being such that an inverted and reversedcorresponding open structural member is nestable within said openstructural member with their respective linear portions overlapping eachother and with each minor flange locatable in an abutting relationshipagainst the underside of the adjacent major flange.

The linear portion may be any suitable length but preferably it extendsalong a major portion of the section axis between the flanges. The term“suitable” is qualified by the particular use of the open structuralmember and where a corresponding member is used the length of the linearportion is such that it enables the linear portions to overlap.

The divergent portion may have any suitable shape. The divergent portionmay be curved, straight, or include a series of straight segments. In apreferred embodiment the divergent portion is a single straight portionthat diverges from the section axis at an acute angle.

Preferably the major flange extends at an acute angle from the divergentportion. When the open structural member is used as a chord with themajor flange outermost, the linear portion being substantially less thanthe length of the section axis between the flanges provides an advantagethat the divergent portion acts in part like a spring to withstandcompression forces substantially acting in the direction of the sectionaxis and thereby resist deformation of the major flange.

The linear portion connects to the minor flange at its end opposite thedivergent portion. Preferably the minor flange extends from the linearportion at an angle of substantially 90 degrees. Alternatively, thelinear portion may include a second divergent portion which extends tothe minor flange. The second divergent portion may be curved, straight,or comprise a series of straight segments.

The minor flange is preferably shorter than the major flange and mostpreferably is shorter than the section of the major flange which extendsbetween an intersection with the section axis and the major flange, andits free end. Preferably the intersection with the section axis occursabout midway across the major flange.

Preferably the flanges are substantially parallel or at least partswhich are substantially diagonally opposite with respect to the sectionaxis are substantially parallel. Preferably the major flange issubstantially parallel with the minor flange.

Preferably the open structural member includes limiting means torestrict lateral movement with respect to the section axis of connectedmembers along the section axis. Preferably the limiting means is areturn flange extending along the free edge of the major flange.

The major and/or the minor flanges preferably both terminate in a returnflange. The return flange preferably returns substantially parallel tothe section axis. Preferably the return flange of the major flange isspaced further from the section axis than the free end of the minorflange so that a reversed and inverted corresponding open structuralmember may nest within the structural member.

The open structural member is preferably asymmetrical in shape andallows the nesting of an inverted and reversed corresponding openstructural member with the minor flange of one open structural memberlocatable within the major flange of the other open structural memberand overlapping of the linear portions.

In another aspect the invention resides in a chord member for a truss,the chord member being an open structural member as described abovewhereby the chord member may be disposed with its major flange outermostand with interconnections between intersecting chord members being madeby overlapping respective linear portions with the minor flange of onechord member being substantially adjacent the underside of the majorflange of the other chord member and the overlapping of the linearportions enabling through fastening of the respective chord members. Insuch arrangement the webs overlap at joints for connection to oneanother such as by bolting or screwing or welding and, if desireddisposed with their minor flanges nested within the major flanges of theopposing chord member.

It is also preferred that the chords of said truss are interconnected bytruss members which may be open section members suitably terminated forweb to web connection to the webs of the top and bottom chord members.

The assembled truss with the open structural member forming the top andbottom chord members with C-section truss members preferably has thechord members proud of the truss members thereby allowing stacking ofthe assembled truss and transportation of the stacks without risk ofdamage to the truss members by the overlying chord members. In contrastconventional box section chords have C-section truss members joined attheir flat surfaces thereby causing the truss members to be proud of thechord members and exposing the truss members to damage during stackingand their transportation.

In a further aspect the invention broadly resides in a composite beamformed by the nesting of two open structural members as described abovein an inverted and reversed orientation with respect to each other withthe minor flange of one member located within the major flange of theother member and overlapping of the linear portions and fastening meansconnecting the open structural members together.

The open structural members may be prevented from lateral displacementwith respect to one another by the fastening means but preferably theyinclude returns along the free edges of the major flanges which restrainlateral displacement of the open structural members with respect to oneanother.

Preferably the nesting of the open structural members as described aboveforms two substantially closed sections thereby providing strength tothe beam.

BRIEF DESCRIPTION OF THE DRAWINGS

Several typical embodiments of the invention will now be described byway of example with reference to the accompanying drawings in which:

FIG. 1 is an end elevation of an elongate open structural member;

FIGS. 2,3, 4 are perspective views of the member;

FIG. 5 is an end elevation of two members nested in reverse and invertedorientation with respect to each other;

FIG. 6a is a front elevation of an assembled truss with open structuralmembers as top and bottom chord members;

FIGS. 6b-g shows various connections on the truss shown in FIG. 6a;

FIGS. 7a-c are views of the interconnection of two open structuralmembers;

FIGS. 8a-c are views of different attachments of C-section truss membersto a chord;

FIGS. 9a-c show alternative connections between chords and trussmembers; and

FIGS. 10a-c show an alternative structural members.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1, 2, 3 and 4 there is shown an elongate openstructural member 10 having a minor flange 12 and a major flange 13separated by a web 14. A longitudinal axis 11 b of the member 10 isshown in FIG. 2. The web 14 includes a planar portion 17 and a divergentportion 18. A section axis 11 a is coincident with the linear portion17.

The minor flange 12 extends from the planar portion 17 at 90 degrees.The minor flange 12 includes a return flange 15. The return flange 15 isparallel to the section axis 11 a.

The divergent portion 18 diverges from the section axis lla at an acuteincluded angle indicated by alpha. The divergent portion 18 is connectedto the major flange 13. The major flange 13 includes a broad planarflange portion 19 which is connected to the divergent portion 18 formingan acute included angle. The major flange 13 also includes a returnflange 20 parallel to the section axis.

As shown in FIG. 5, two elongate open structural members 30, 31 asdescribed above are able to be nested with one member being in reverseand inverted orientation with respect to the other. To effect nestingminor flanges 32 a and 32 b are located within major flanges 33 b and 33a respectively in abutting relationship. In this position the respectiveweb portions 34 a, 34 b partly overlie each other thereby allowingfasteners to join both members 30, 31 to prevent lateral movement. Theabutting relationship of the respective flanges 32 a, 32 b, 33 a, 33 bprevents movement along the section axis. The nesting of the twoelongate members forms two closed sections 35, 36 which provide strengthand stiffening to the composite member.

Roof trusses 40 as shown in FIGS. 6a-g are constructed with elongateopen structural members forming top and bottom chords 41,42 andC-section truss members 43. The connection of the top chord 41 to thebottom chord 42 is shown in FIG. 6b. The major flanges 44,45 of the topand bottom chords 41 and 42 respectively are outermost. The minor flange46 of the top chord 41 is partially located and confined in major flange45. The rearward flat side 47 of top chord 41 partly overlaps frontwardflat side 48 of the bottom chord 42. There is shown an intermediateconnection plate 49 between sides 47 and 48. The connection plate 49 isattached to the bottom chord 42 by bolts 50, 51 and to the top chord 41by bolts 50, 52. An alternative connection is shown in FIG. 9c where topchord 60 is bolted to bottom chord 61 at 62.

Connections of the truss members 43 to the chord members 41,42 are shownin FIGS. 6c, 6 d, 6 f. In FIG. 6d the truss members 43 are crimped andjoined to the top chord 41 by bolt 70. In FIG. 6e the truss members 43are attached to the bottom chord 42 by bolt 72. The underlying trussmembers are at least crimped to accommodate the connection. Theconnection shown in FIG. 6c has the truss member 43 connected by bolt 71to the bottom chord 42. The chords 41,42 are proud of the truss members43 in the truss 40.

The apex 80 of the truss 40 is shown in FIGS. 6f, 6 g. An apex plate 81serves to connect top chords 41 by bolts 82. The apex plate 81 hasrecessed ribs 83 to provide additional stiffening. The apex plate 81also has a recess 84 for the location of a C-section truss member 43.The C-section truss member 43 is connected to the apex plate 81 by bolt85. Alternative connections in an apex are shown in FIG. 9a and 9 b. InFIG. 9a top chords 63 and C-section truss members 64 are connected bybolt 65. Similarly in FIG. 9b the top chords 66 and C-section trussmember 67 are connected by bolt 68.

In FIGS. 7a-c there is shown chords 90,91 with major flanges 92,93outermost and minor flange 94 located partially within the major flange92.

In FIGS. 8a-c there is shown attachment of crimped C-section trussmembers 95 to elongate open structural member chords 96 by bolts 97. TheC-section truss member 95 has end 98 crimped presenting a flat surface99 for connecting to the chord 96. The flat surface 99 is attached tothe side of the web portion 100 opposite the narrow flange 101.

The embodiment described above provides a number of advantages includingefficient roll forming for chord production; provision of a strengthenedand stiffer open section member chord with proper orientation of themajor flange outermost; the ability to treat or coat the entire chord orcomposite beam or truss having open sections prior to use; compact trussstacking with chords being proud of truss web members thereby minimisingdamage to the truss members during transportation and reducing transportand storage costs; the ability of the chords to overlap forinterconnection while maintaining the overlapped chords in line oneabove the other for symmetry of the truss and to be easily fastenedtogether at terminations.

It will of course be realised that while the foregoing has been given byway of illustrative example of this invention, all such and othermodifications and variations thereto as would be apparent to personsskilled in the art are deemed to fall within the broad scope and ambitof this invention as is herein set forth.

What is claimed is:
 1. An elongated structural member having across-section including a minor flange, a major flange, and a webinterconnecting said flanges and having a section axis at right anglesto the longitudinal axis of the structural member and wherein: said webincludes a linear portion, which extends substantially coincident withthe section axis, and a divergent portion which extends to one side ofsaid section axis; said minor flange laterally extends from said sectionaxis to said one side; said major flange extends from said divergentportion to the opposite side of said section axis and includes a majorflange return which is spaced from the opposite side of the section axisby an amount substantially corresponding to the minor flange extendsfrom the one side of the section axis, and the section configuration ofthe structural member being shaped such that a correspondingly shapedstructural member can be inverted, inclined and nested with saidstructural member with the respective linear portions abutting eachother and with each minor flange in an abutting relationship with theadjacent major flange whereat it is partially confined by thecorresponding major flange return such that separation of the abuttinglinear portions is prevented.
 2. An elongate structural member asclaimed in claim 1 wherein said linear portion extends from the minorflange along a major portion of the section axis between the flanges andsaid divergent portion extends at an acute angle from the section axis.3. A truss including upper and lower chords formed by elongatestructural members as claimed in claim 2, wherein the longitudinal axesof the upper and lower chords are inclined at an acute angle withrespect to each other and wherein the linear portions abut adjacent theeave line of the truss for connection to one another and the minorflange of each one of the chords abuts the major flange of the otherchord at the eave line and is partially confined by the major flangereturn of the other chord such that separation of the abutting linearportions is prevented.
 4. An elongate structural member as claimed inclaim 1 wherein the minor flange includes a minor flange return, theminor flange return being adapted to abut a major flange return of aninverted and inclined like-sectioned structural member nested therein.5. A truss including upper and lower chords formed by elongatestructural members as claimed in claim 4, wherein the longitudinal axesof the upper and lower chords are inclined at an acute angle withrespect to each other and wherein the linear portions abut adjacent theeave line of the truss for connection to one another and the minorflange of each one of the chords abuts the major flange of the otherchord at the eave line and is partially confined by the major flangereturn of the other chord such that separation of the abutting linearportions is prevented.
 6. A truss including upper and lower chordsformed by elongate structural members as claimed in claim 1, wherein thelongitudinal axes of the upper and lower chords are inclined at an acuteangle with respect to each other and wherein the linear portions abutadjacent the eave line of the truss for connection to one another andthe minor flange of each one of the chords abuts the major flange of theother chord at the eave line and is partially confined by the majorflange return of the other chord such that separation of the abuttinglinear portions is prevented.
 7. A chord for a truss, the chordincluding in section: a web including a linear portion; a minor flangeconnected to the web extending from the web in a first direction; and amajor flange connected to the web, extending from the web in a seconddirection opposite the first direction and spaced from and parallel tothe minor flange, the major flange including a major flange return;wherein the chord is configured such that a second like-sectioned chordcan be inverted, inclined and nested with the chord, with the respectivelinear portions of the webs abutting and with the minor flange of eachchord abutting the major flange of the other chord and partiallyconfined by the major flange return of the other chord wherebyseparation of the abutting linear portions of the webs is prevented. 8.A truss including a pair of chords as claimed in claim 7, an upper chordhaving the major flange uppermost, and a lower chord having the majorflange lowermost, wherein the longitudinal axes of the upper and lowerchords are inclined with respect to each other and wherein the upper andlower chords intersect and nest together at the eave line.
 9. A chordfor a truss, the chord including in section: a web including a linearportion; a minor flange connected to the web and extending from the webin a first direction; and a major flange connected to the web, andspaced from and parallel to the minor flange, the major flange extendingfrom the web in a second direction opposite the first direction, themajor flange including a major flange return, wherein the chord isconfigured such that a second like-sectioned chord can be inverted,inclined and nested with the chord, with the respective linear portionsof the webs abutting and with the major flange and major flange returnof each chord closely enveloping the minor flange of the other chordwhereby separation of the abutting linear portions of the webs isprevented.
 10. A truss including a pair of chords as claimed in claim 9,an upper chord having the major flange uppermost, and a lower chordhaving the major flange lowermost, wherein the longitudinal axes of theupper and lower chords are inclined with respect to each other andwherein the upper and lower chords intersect and nest together at theeave line.
 11. A chord for a truss, the chord including in section: aweb including a linear portion; a first flange connected to the web andhaving a lateral portion extending in a first direction; a second flangeconnected to the web and spaced from and parallel to the first flange,the second flange including a lateral portion extending in a seconddirection different than the first direction and a second flange return;wherein the chord is configured such that a second like-sectioned chordcan be inverted, inclined and nested with the chord, with the respectivewebs abutting and with the first flange of each chord abutting thesecond flange of the other chord and partially confined by the secondflange return of the other chord whereby separation of the abutting websis prevented.
 12. A truss including a pair of chords as claimed in claim11, an upper chord having the second flange uppermost, and a lower chordhaving the second flange lowermost, wherein the longitudinal axes of theupper and lower chords are inclined with respect to each other andwherein the upper and lower chords intersect and nest together at theeave line.
 13. A chord for a truss, the chord including in section: aweb including a linear portion; a first flange connected to the web andhaving a lateral portion extending in a first direction; a second flangeconnected to the web and spaced from and parallel to the first flange,the second flange including a lateral portion extending in a seconddirection different than the first direction and a second flange return;wherein the chord is configured such that a second like-sectioned chordcan be inverted, inclined and nested with the chord, with the respectivewebs abutting and with the first flange of each chord abutting thesecond flange of the other chord and partially confined by the secondflange return of the other chord whereby separation of the abutting websis prevented.
 14. A truss including a pair of chords as claimed in claim13, an upper chord having the second flange uppermost, and a lower chordhaving the second flange lowermost, wherein the longitudinal axes of theupper and lower chords are inclined with respect to each other andwherein the upper and lower chords intersect and nest together at theeave line.
 15. A truss including: a lower chord including in section: aweb having a linear portion and a divergent portion which extends to oneside of the linear portion, a minor flange extending from the linearportion to the one side of the web, and a major flange extending fromthe divergent portion back to the other side of the web and including amajor flange return; an upper chord of the same section as the lowerchord, wherein the upper chord is inverted and inclined with respect tothe lower chord and wherein the upper and lower chords nest together atthe eave line of the truss with the respective linear portions abuttingand with the respective minor flanges abutting the respective majorflanges and partially confined by the major flange returns.
 16. A trussincluding: a lower chord including in section: a web, a minor flange,and a major flange; an upper chord of the same section as the lowerchord, wherein the upper chord is inverted with respect to the lowerchord, and a line drawn through the longitudinal axis of the upper chordis not parallel to a line drawn through the longitudinal axis of thelower chord, and the upper and lower chords nest together at the eaveline of the truss with the respective webs abutting and with therespective minor flanges abutting the respective major flanges.
 17. Atruss as claimed in claim 16, wherein the major flange includes a majorflange return, the minor flange being partially confined by the majorflange return such that separation of the abutting webs is prevented.18. A truss including: a lower chord including in section: a web, afirst flange, and a second flange; an upper chord of the same section asthe lower chord, wherein the upper chord is inverted with respect to thelower chord, and a line drawn through the longitudinal axis of the upperchord is not parallel to a line drawn through the longitudinal axis ofthe lower chord, and the upper and lower chords nest together at thecave line of the truss with the respective webs abutting and with therespective first flanges abutting the respective second flanges.
 19. Atruss as claimed in claim 18, wherein the second flange includes asecond flange return, the first flange being partially confined by thesecond flange return such that separation of abutting webs is prevented.20. A method of forming a truss including: providing a pair oflike-sectioned chords, each chord having in section a web, a minorflange and a major flange; inverting one chord relative to the other andinclining the longitudinal axes of the chord with respect to each otherand intersecting and nesting the chords at the eave line of the trusssuch that the respective webs abut and such that the respective minorflanges abut the respective major flanges.
 21. A method as claimed inclaim 20, wherein the major flange includes a major flange return, theminor flange being partially confined by the major flange return suchthat separation of abutting webs is prevented.
 22. A method of forming atruss including: providing a pair of like-sectioned chords, each chordhaving in section a web, a first flange and a second flange; invertingone chord relative to the other and inclining the longitudinal axes ofthe chords with respect to each other and intersecting and nesting thechords at the eave line of the truss such that the respective webs abutand such that the respective first flanges abut the respective secondflanges.
 23. A method as claimed in claim 22, wherein the second flangeincludes a second flange return, the first flange being partiallyconfined by the second flange return such that separation of abuttingwebs is prevented.